Engine Light

1998 Ford Windstar. My engine light comes on for several days then will go off for several more days and back on again. The van seems to be running well and have no problems starting seems the light is on for no reason more of a nusciance than a problem. If I disconnect the battery and reconnect it the light stays off for several days but no fear it will be back on again
Any suggestions
Thanks
Ed

Next time it comes on take it to Autozone they will pull the code for free.Post the number they give on here and we can tell you were to start looking.Could be your IAC valve, Mass air flow sensor or any number of things.